Former San Francisco 49ers safety Eric Reid is following in the footsteps of former teammate Colin Kaepernick, filing a grievance against the NFL after going unsigned through the first two months of free agency.

Reid is alleging that he remains unsigned as a result of collusion by the owners after joining Kaepernick in his protests during the national anthem. Reid is represented by Mark Geragos, who also represents the former 49ers quarterback.

The NFL Players Association confirmed the filing of a grievance on Wednesday with the following statement:

"Our union is aware that Eric Reid and his legal representatives filed a collusion claim, which will be heard through the arbitration process as spelled out in our collective bargaining agreement. Our union supports Eric and we are considering other legal options to pursue."

Reid took to Twitter in March and stated that the anthem protests were the reason he remained unsigned.

"The notion that I can be a great signing for your team for cheap, not because of my skill set but because I've protested systemic oppression, is ludicrous. If you think [it] is, then your mindset is part of the problem too," Reid tweeted three days after free agency opened.

While Kaepernick was the first player to kneel during the national anthem to protest racial inequality and has become the face of the anthem protests, Reid was the first person to kneel alongside Kaepernick when they were teammates in San Francisco. Reid kneeled beside Kaepernick for the entire 2016 season.

Kaepernick spent last year out of football after no team offered him a contract and filed his grievance against the NFL in October.

Reid played in 13 games with 12 starts for the 49ers last season, finishing with 52 tackles, two interceptions, and four pass defences. The 2013 first-round pick has started 69 games over his five-year career with the 49ers, accumulating 264 tackles, 10 interceptions, and 36 pass defences.

A Pro Bowl safety in 2013, Reid has stated he no longer plans to kneel during the anthem, but has received just one visit as a free agent – from the Cincinnati Bengals in April.